Dear Thomas,
Thank you for getting back to me. The only proof that we have is in the finished product that we are putting down. It is so dry and brittle, that is just falls apart. It is our word against their word. We have been taking pictures and keep samples of the material that has been sold to us. Just in case we do move forward. I have spoke with guys who work in the Labs, that run test on this type of material, and they have given me advice on what to do and how to handle the situation. We have lost thousands of dollars and now are loosing jobs due to this defective material.It is not affecting our bottom line here. I have been in the business for over 34 years, as a licensed contractor for the past 24 years.

Sounds like you have a real problem. If you can get some sort of lab test result on the actual material showing that it is not proper, then it no longer is an "our word against theirs" situation.